Switch-block.



No. 768.197. f PATENTED AUG. z3, 1904. I. B. SMITH.

SWITCH BLOCK.

APPLICATION FILED DEO 3 1903 N0 MODEL.

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' lV-Hitman UNITED STATESl Patented August 23, 1904.

PATENT OEEICE.

SWITCH-BLOCK.

SPECIFICATION forming part of Letters Patent No. "268,197, dated August 23, 1904. Application lerl December 3, 1903. Serial No. 183,639. (No model.)

To all whom t may concern:

Be it known that I, IRvING B. SMITH, a citi- Zen of the United States, residing at Philadel# phia, in the county of Philadelphia and State of Pennsylvania, have inventednew and useful Improvements in Switch-Blocks, of which the following is a specification.

This invention relates to switch-blocks or contact-segments for rheostats, starters, controllers, and other apparatus to which the invention may be applied, and has for its objects the production of a switch-block or contact-segment wherein the wearing-surface may be cheaply and easily renewed and v in which a maximum area of contact is presented between the block or segment and the sliding switch-contact or brush.

Further objects of the said invention are to effect the most direct and positive connection between the cable-head, cable, or other conducting-lead connected to the block and the contact-surface which the brush engages, to securea rigid and simple mechanical conlstruction without impairing the electrical features, to sodispose the metal of said block: or segment as to most eliiciently convey the current from said brush and dissipate the heat arising therefrom, and to eliminate from the electric circuit the screws or bolts which are employed for attaching the block to its base or support. y

To the above ends my said invention consists in the combination and arrangement of parts herein described, and more particularly pointed out in the claims.

Referring to the accompanying drawings, in which is illustrated one specific form of my invention and a modification thereof, Figure 1 is a top plan Iview of three of the switchblocks and related parts arrangedupon a suitable base, the latter being broken away; Fig.

2, a section along the line m of Fig. 1, and Fig. 3. a central vertical section of a modified f form of said block and its related parts.

.In the embodiment of my invention herein shown the contact-surface of the block is formed of aplate or segment 1, preferably of brass or copper, and this plate is reinforced by a backing or support 2, of some baser and preferably stiffer metal-such, for example, as iron. The plate l is secured near one end to the backing 2 by a small screw 3, while both plate and backing are formed with a bend of substantially ninety degrees at their outer ends where connection is made with the cable, cable-lug, wire, or other conductinglead to which the block is connected. rlhe electrical requirements as to current-carrying capacity determine the minimum amount of metal that may be used in forming the contact surface or plate 1, and in making the connection from such surface to the cable or cable-lug, and it is desirable usually not to exceed this minimum amount. vical requirements of strengthv and stiffness, however, are met by reinforcing the plate l, as shown. It is desirable that such reinforcing-piece,`usually of inferior current-carrying capacity as compared with the plate l, f

owing to its greater ohmic resistance, shall not necessarily form a portion of the electrical circuit leading .from the brush-contact to the cable or cable-lug, unless, indeed, it forms a multiple-circuit, inwhich case it does no harm and may be an advantage. In other words, theplates 1v and12 may or may not be insulated from eachother,v as the `occasion demands. The block is secured to the slate or other insulating-base 4: bymeans of the countersunk bolts 5 and nuts 6, the Vsaidbolts passing through the base and the backingor reinforcing plate 2. The'functionof the bolts 5 is therefore purely mechanical, since they form no part of the electric circuit. This fact alone will admit of a saving of material, since the bolts 5 may in this case vbe made much smaller than would be the Vvcase were they employed in a current-carrying capacity-for they need have only mechanical strength and not the current-carrying capacity which each particular switch might have. An additional advantage gained by the eliminationV of attaching screws or bolts from the electriccircuit is that numerous contacts, whichtheir inclusion in such circuit would entail, are gotten rid ofHnamely, the contacts at the heads of the screws and the contacts at` the nuts and also The cable-head 7, cable, wire, or other conductor forming the lead to the block is attached thereto by means of a stud 8, tapped at its upper end to receive a nut 9 and provided at its other end with a preferably square shank 10, which passes through a square opening 11 in the overturned end of the plate 2. The end of a shank 10 is upset or riveted to form the head 12, whereby the stud is held rigidly upon the said plate 2. While I have shown the shank 10 square to prevent the rotation of the stud, this may be prevented just as well and more cheaply by making the shank round and upsettingit in the square hole 11 and riveting' the end. The connecting-stud 8 passes through the overturned end of the plate 1 and preferably engages the same at that point. Preferably this contact-plate 1 is slotted, as at 13, Where it so engages said stud, thereby permitting the said contact-plate to be most readily removed, since a slot will permit removing the contact-plate without removing the nut or cable-lug, cable, or other conductinglead. It is, in fact, only necessary to loosen the nut 9 somewhat and remove the small screw 3 at the other end of the plate, when the latter may be readily removed and another put in its place. It will therefore be seen that the necessity of renewing a whole switch-block when its contact-surface becomes deteriorated is by this vinvention avoided, thereby effecting' a considerable saving in the cost of material. Moreover, the first cost of such a block would be less than if it were made throughout of the metal of which the con tactsurface is composed, since the backing may be of much less expensive material than the conducting-surface.

Making the cable connections around the outer end of the blocks in the manner shown admits of the use of an insulating-base of much smaller diameter for a given piece-of apparatus than would by the usual constructions be required.

In Fig. 3 is shown a form of the invention in which the backing 2 is raised from the base 4 and supported upon an intervening block 14; of any suitable metal or other material, beyond which the plate 1 and backing 2 pass to form the extension 15. If desired, this block 14 may be simply an extension of the base 1. 'Ihe contact segment or plate 1 is shown in this case as bent at its inner end and hooked around the end of the backing 2 and is provided at such end with a small slot 16, which engages a pin 17 in the backing to prevent sidewise play or slipping. In other respects this construction is the same as shown in Fig. 1. In Fig. 3, however, the cable-lug is shown replaced by a Wire 18, held between the washers 19. The primary object of the form of the invention shown in Fig. 3 is to provide a construction whereby the switch-arm may be provided with m 2ans for engaging the block both on top of the plate l and on the under side of the extension forming the hooked portion, thereby equalizing the strain on the shaft which carries the switch-arm. This extension of the block may or may not assist in conducting the currentfrom the contact-blocks to the switch-arm. Hence the end of the plate 1 may be made as shown in Fig. 1, or as otherwise desired.

Other modifications of the invention herein described may be made without departing from the spirit thereof.

That I claim ism- 1. In a switch-block, a sumiorting-plate or backing, a removable contact plate carried thereby, and means independent of said contact-plate for securing the block to a support.

2. In a switch-block, a supporting-plate or backing, a removable contact-plate carried thereby, means for attaching the said contactplate to the backing near one end of the block, and a cable connection adapted to hold the said contact-plate in position at the other end of said block.

3. In a switch-block, a supporting-plate or backing, a removable contact-plate carried by said backing and having at one end an open-end slot, a screw attaching the contact-plate to the backing at the end of said block opposite said slot, 4and a binding-post carried by said hacking and engaging said slot in said contactplate.

1. In a switch-block, a sulmorting-plate or backing, a removable contact-plate carried by said backing and having an open-end slot at one end thereof, said hacking' and contactplate forming at the end of the block at which said slot is located an angle with the main body of the block, detachable means for attaching the said contact-plate to the backing at the end of said block opposite said slot, a bindingpost carried by said backing and engaging' said slot, and attaching-screws secured to the said backing independently of said contactplate, for securing said block to a support.

The combination with a switch-base of the character described, of a switch block mounted thereon, said switch-block comprising a supporting-plate or backing, a removable contact -plate carried thereby .and provided at one end with an open-end slot, said backing and contact-plate forming a bend at their outer ends where they extend over the edge of the said base, a bimling-post'I secured to the portion of the backing extending over f the edge of said base and adapted to engage the said slot, and attaching-screws passing through said base and said backing.

6. The combination with a switch-base, of the character described, of a switch-block comprising a supporting-plate or backing, a removable contact-plate mounted thereon,

IOO

means for connecting said contact-plate to a In testimony whereof I have signed my name conducting-lead, ,a block interposed between to this speeieaton n the presence of two subsad backing and said hase and beyond Which scrbing Witnesses.

the said backing extends at one end thereof to form' a space between it and the said base, and means for securing said switch-block to said Switch-base'. 'f

. IRVING B. SMITH. Witnesses:

4WM. O. HOWELL, LINDA COPE SMITH. 

